A known seat reclining apparatus for a vehicle is disclosed in JP2009-201663A (hereinafter referred to as Patent reference 1). According to the known seat reclining apparatus for the vehicle, a pair of known recliners is provided at a seatback so as to be arranged at a side, in a width direction of a seat for the vehicle, at which a shoulder belt anchor is provided and to which a large load is applied in case of, for example, a vehicle collision. Thus, strength is assured against the large load applied to the seatback. A drive source (an electric motor) is connected to the recliners for driving the recliner to allow lower arms and upper arms, which are connected to the recliners, to pivot relative to each other. The lower arms are fixedly attached to a lower side frame constituting a framework of a seat cushion and the upper arms are fixedly attached to an upper side frame constituting a framework of the seatback. Thus, a tilt angle of the seatback relative to the seat cushion may be changed.
According to the above-explained known seat reclining apparatus for the vehicle, the electric motor is generally used as the drive source and provides a constant driving speed. The driving speed of the electric motor may be appropriate for the adjustments of the tilt angle of the seatback relative to the seat cushion. However, for example, when a passenger on a rear seat of the vehicle egresses the vehicle via a door positioned in a vicinity of a front portion of the vehicle by tilting the seatback to a large extent, which is positioned to be a partition between a front seat and the rear seat, the passenger may find the driving speed of the electric motor rather slow. In addition, the seat reclining apparatus for the vehicle is essentially expected to have an adequate load resistance performance.
A need thus exists for a seat reclining apparatus for a vehicle, which is not susceptible to the drawback mentioned above.